A combined NSMC and pole series expansion approach for UXO discrimination

This paper combines the normalized surface magnetic charge (NSMC) model and a pole series expansion method to determine the scattered field singularities directly from EMI measured data, i.e. to find a buried object location and orientation without solving a time consuming inverse-scattering problem. The NSMC is very simple to program and robust for predicting the EMI responses of various objects. The technique is applicable to any combination of magnetic or electromagnetic induction data for any arbitrary homogeneous or heterogeneous 3-D object or set of objects. In this proposed approach, first EMI responses are collected at a measurement surface. Then the NSMC approach, which distributes magnetic charge on a surface conformal, but does not coincide to the measurement surface, is used to extend the actual measured EMI magnetic field above the data collection surface for generating spatially distributed data. Then the pole series expansion approach is employed to localize the scattered fields singularities i.e. to determine the object's location and orientation. Once the object's location and orientations are found, then the total NSMC, which is characteristic of the object, is calculated and used for discriminating between UXO and non-UXO items. The algorithm is tested against actual EM-63 time domain EMI data collected at the ERDC test-stand site for actual UXO. Several numerical results are presented and discussed for demonstrating the applicability of the proposed method for determining buried objects location as well as for discriminating between objects on interested from non-hazardous items.